and the dissipative coefficient given in a variant of the WLI where the inflaton couples to a pair of scalars \(\chi _{1,\,2}\)  instead of fermions [1]}. We can call this the “Scalar Warm Little Inflation” (SWLI) model.
As in the original WLI, the inflaton is the relative phase between two scalars fields \(\phi _{1,\,2}\)  charged under a \(U(1)\)  broken gauge symmetry at a scale \(M\) , now coupled to a pair of scalars \(\chi _{1,\,2}\)  with coupling \(g\) . The system satisfies the interchange symmetry \(\phi _1 \leftrightarrow i \phi _2\) , \(\chi _1 \leftrightarrow \chi _2\) . This symmetry ensures that the scalar fields \(\chi _1\) , \(\chi _2\)  can be “light” during inflation, in the sense of having masses below the temperature bath, while avoiding large thermal radiative corrections to the inflaton potential. The interaction Lagrangian is given by:
\({\cal L}_I = \frac{1}{2} g^2 |\phi _1 + \phi _2|^2 |\chi _1|^2+ \frac{1}{2} g^2 | \phi _1 - \phi _2 |^2 |\chi _2|^2 \,,\) 
